Boston firefighters would get an 18.8 percent pay raise under a contract deal that city labor officials said includes measures to improve safety and management in the Fire Department.

The six-year pact, which firefighters are expected to vote on next week, would cost the city $92.4 million, say city officials, and it comes seven months after an arbitrator put an end to acrimonious negotiations between the city and police officers
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Firefighters have been without a contract for about three years. Mayor Martin J. Walsh had promised during last year’s campaign that he would move swiftly to reach a resolution.

The firefighters’ raise would be less than the 25.4 percent pay increase police officers received from the arbitrator last year, a boost that became a hot topic in last year’s mayoral race.

The tentative firefighter agreement includes a baseline 14 percent pay increase, along with additional funds that preserve a unique 0.5 percent pay perk known as the transitional career award program, which firefighters get each time there is a pay increase.

Walsh administration officials said the union agreed to a lower pay package than police received to end the long-stalled negotiations.

“These guys came in much lower than the 25 percent’’ awarded to police officers, said Joseph Rull, chief of operations in the Walsh administration, who oversees the city’s labor department.

‘My job is to look out for my firefighters and also look out for what is fair for the citizens of Boston.’

Richard Paris, Firefighters union president

Richard Paris, president of firefighters union Local 718, called negotiating with Walsh’s team refreshing compared to the administration of Mayor Thomas M. Menino.

Paris said that there were at least three bargaining sessions and that the sides quickly agreed to a deal before the deaths of two firefighters last month in a Back Bay blaze.

The firefighters union “along with the city, want to keep libraries open, want to keep our streets clean,’’ Paris said. “We don’t want to see layoffs. We want to keep jobs in the city. We don’t want to break the city.

“My job,” he said, “is to look out for my firefighters and also look out for what is fair for the citizens of Boston.”

Since announcing the tentative deal April 19, Walsh, a former high-ranking trade union official, had refused to divulge details, saying he was honoring his agreement with the union and would wait until its 1,400 members voted. The union held a pair of meetings at its union hall in Dorchester this week, with members of the executive board explaining the contract.

With hundreds of firefighters armed with details of the deal, Walsh’s representatives approached the Globe Thursday, offering an interview with members of the mayor’s bargaining team, including his chief of operations, labor chief, and budget director, as well as the union president.

A Globe reporter, a Globe columnist, and a WBUR radio reporter met with the administration and union officials in the Eagle Room on the fifth floor of City Hall, where a one-sheet summary of contract highlights was provided.

Rull said the city’s team and the fire union settled the contract after roughly 15 hours of negotiations. He said that from the beginning, the sides agreed to keep “all the numbers in the room” until fire union members had a chance to view the proposed contract.

Walsh participated in the talks periodically.

“We are not in the business of negotiating through the press or through back channels,” Rull said. “It’s sitting in the room and looking in the eye and having that trust and faith. That’s why we did honor our word with these guys.”

The union is expected to vote on the deal next Thursday, and Paris said he is confident his members will ratify the contract. In 2013, firefighters were paid an average of $97,000.

Fiscal watchdog Samuel R. Tyler, who has seen the contract, said it is a good start, albeit a costly one. He said he wished there was language in the tentative deal that would achieve further cost savings.

“These are incremental reforms,’’ said Tyler, president of the nonprofit Boston Municipal Research Bureau. “It’s not a giant leap.”

The proposed two-part contract, which is retroactive to July 1, 2011, and extends to June 30, 2017, leaves in place longevity benefits, vacation perks, and the transitional career award program.

The tentative deal includes retroactive pay, starting with a 1 percent pay increase the first year, then 2 percent the second, and 3 percent the third.

Beginning in July, firefighters will get a 3 percent pay increase for two years and then a 2 percent pay hike in 2016.

City and union officials described the 2 percent increase in the final year as a launching pad for negotiations with other unions in the city, beginning in 2017.

The issue of wage parity between the city’s fire and police unions has long framed contract negotiations. The police union has argued that officers’ base pay overall is lower than
firefighters receive. The arbitrator’s award last year to police officers cost taxpayers $80 million over six years.

The city’s labor chief, Paul Curran, said the proposed pact with firefighters combined with the higher base pay awarded police officers last year, addresses that difference.

“It helps to close the gap,” he said. “But it doesn’t complete it.”

Curran said the city secured language in the firefighters’ contract that would spark reforms, improvements that might have gone unfulfilled if the talks had gone to arbitration.

“The last time we sat down with the patrolmen, we [went] through arbitration. We got a 25.4 award with six years, with minimal’’ concessions to the city, Curran said. “The time before that, we went to arbitration with the fire union and got an expensive award . . . with minimal management gain.”

The tentative firefighter deal would, for instance, require firefighters who have been injured to return to full duty sooner. In addition, the city and the union agreed to take steps to curb certain overtime abuses by firefighters.

And the contract would also require that firefighters must have at least three years on the job and extra training in fire operations to take the lead at fire scenes. Now, at some fire companies, firefighters with one year on the job serve as what is known as the senior man, filling in for a captain or lieutenant.

The tentative contract requires that anyone serving as a senior man must take a civil service promotional exam and demonstrate a knowledge of fire ground operations and performing the job at a higher grade.

The union was able to keep longevity benefits and vacation perks. Firefighters who serve as hazardous materials and technical rescue specialists will receive a larger stipend.

In addition, firefighters who are certified emergency medical technicians get a 2 percent pay increase every other year. Under the current contract, they got a flat check amounting to about a week’s worth of overtime every other year.

Tyler said the 2 percent boost, which will bump up the firefighters’ pension, is troubling because of the hidden cost.

“It adds to the city’s pension liability,’’ Tyler said. “That doesn’t help with the parity issue. It broadens the gap. Already the average firefighter makes more than the average police officer. Firefighters retire with a higher pension. This just adds to that.”